The 29-year-old Avila was limited to 67 games with the Detroit Tigers this past season with a bone bruise in his left knee, batting .191 with four home runs and 13 RBIs. He was an All-Star as recently as 2011, when he also won a Silver Slugger award. He also finished 12th in the American League MVP voting that season.
This past season, White Sox catchers combined to finish ninth in the AL in batting average (.230), 11th in OBP (.293) and 10th in slugging percentage (.376).
"Alex has a tremendous reputation as a leader in the clubhouse," White Sox general manager Rick Hahn said. "Obviously he knows the division quite well and provides a nice balance from an offensive standpoint given the left-handed bat and his ability to get on base and provide some power against right-handed pitching."
The signing forms a reunion of sorts between Avila and White Sox closer David Robertson, who were teammates in 2006 at the University of Alabama. Avila was selected by the Tigers in the fifth round of the 2008 draft and made his major league debut in 2009.
In 683 games over seven seasons, all with the Tigers, Avila has batted .242 with a .345 on-base percentage and a .397 slugging percentage. In 2011, while helping the Tigers to the postseason, he batted .295 with 33 doubles, 19 home runs, 82 RBIs and a .506 slugging percentage.
Avila's father, Al Avila, is the general manager of the Tigers, having replaced Dave Dombrowski in August.